More and more people select cloud as an important tool for data storing, processing and sharing, as a result, the data in cloud increases rapidly, including some sensitive and privacy information. It is a vital problem to manage the authorizations of hosted data in cloud for confidentiality and effectiveness of access control. This study proposes a proxy re-encryption based assured update scheme of authorization for cloud data (PAUA) in light to solve the above mentioned problem. Firstly, the aims and assumptions of PAUA are given. Secondly, the system model and algorithm are shown. Finally, the comparisons with PAUA and the current status are carried out. The PAUA reduces the encryption and decryption work of personal users. Meanwhile, it ensures the permission updating by dividing the parameters of re-encryption key generation.